/*
 * Copyright (c) 2021, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.svm.core.headers;

import static com.oracle.svm.core.Uninterruptible.CALLED_FROM_UNINTERRUPTIBLE_CODE;

import org.graalvm.nativeimage.ImageSingletons;
import org.graalvm.nativeimage.UnmanagedMemory;
import org.graalvm.nativeimage.c.type.CCharPointer;
import org.graalvm.nativeimage.c.type.CCharPointerPointer;
import org.graalvm.word.PointerBase;
import org.graalvm.word.SignedWord;
import org.graalvm.word.UnsignedWord;

import com.oracle.svm.core.Uninterruptible;
import com.oracle.svm.core.imagelayer.ImageLayerBuildingSupport;
import com.oracle.svm.core.layeredimagesingleton.LayeredImageSingletonSupport;
import com.oracle.svm.core.memory.NativeMemory;
import com.oracle.svm.core.memory.NullableNativeMemory;
import com.oracle.svm.core.memory.UntrackedNullableNativeMemory;
import com.oracle.svm.core.traits.SingletonLayeredInstallationKind;
import com.oracle.svm.core.traits.SingletonTraitKind;

import jdk.graal.compiler.api.replacements.Fold;

/** Platform-independent LibC support. */
public class LibC {
    public static final int EXIT_CODE_ABORT = 99;

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static int errno() {
        return libc().errno();
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static void setErrno(int value) {
        libc().setErrno(value);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static <T extends PointerBase> T memcpy(T dest, PointerBase src, UnsignedWord n) {
        return libc().memcpy(dest, src, n);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static <T extends PointerBase> int memcmp(T s1, T s2, UnsignedWord n) {
        return libc().memcmp(s1, s2, n);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static <T extends PointerBase> T memmove(T dest, PointerBase src, UnsignedWord n) {
        return libc().memmove(dest, src, n);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static <T extends PointerBase> T memset(T s, SignedWord c, UnsignedWord n) {
        return libc().memset(s, c, n);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static void exit(int status) {
        libc().exit(status);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static void abort() {
        /*
         * Using the abort system call has unexpected performance implications on Oracle Enterprise
         * Linux: Storing the crash dump information takes minutes even for tiny images. Therefore,
         * we just exit with an otherwise unused exit code.
         */
        exit(EXIT_CODE_ABORT);
    }

    /**
     * May only be used to free memory that was allocated by the libc or other native code. Do
     * <b>NOT</b> use this method when freeing memory that was allocated via internal APIs such as
     * {@link NativeMemory}, {@link NullableNativeMemory}, {@link UntrackedNullableNativeMemory}, or
     * {@link UnmanagedMemory}.
     */
    @Uninterruptible(reason = CALLED_FROM_UNINTERRUPTIBLE_CODE, mayBeInlined = true)
    public static void free(PointerBase ptr) {
        libc().free(ptr);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static UnsignedWord strlen(CCharPointer str) {
        return libc().strlen(str);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static CCharPointer strdup(CCharPointer str) {
        return libc().strdup(str);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static int strcmp(CCharPointer s1, CCharPointer s2) {
        return libc().strcmp(s1, s2);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static int isdigit(int c) {
        return libc().isdigit(c);
    }

    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
    public static UnsignedWord strtoull(CCharPointer string, CCharPointerPointer endPtr, int base) {
        return libc().strtoull(string, endPtr, base);
    }

    @Fold
    public static boolean isSupported() {
        return ImageSingletons.contains(LibCSupport.class) || isInstalledInInitialLayer();
    }

    private static boolean isInstalledInInitialLayer() {
        if (ImageLayerBuildingSupport.buildingExtensionLayer()) {
            var trait = LayeredImageSingletonSupport.singleton().getTraitForUninstalledSingleton(LibCSupport.class, SingletonTraitKind.LAYERED_INSTALLATION_KIND);
            return SingletonLayeredInstallationKind.getInstallationKind(trait) == SingletonLayeredInstallationKind.InstallationKind.INITIAL_LAYER_ONLY;
        }
        return false;
    }

    @Fold
    static LibCSupport libc() {
        return ImageSingletons.lookup(LibCSupport.class);
    }
}
